It seems that the output has length only 1, so s[0] does not work.

That's a `solve`

idiosyncrasy :

Each solution of a(n) (system of) equation(s) for `n>1`

variables is either a list of `n`

equations (default) or a dictionary with `n`

keys (when using `solution_dict=True`

). `solve`

returns a list of such solutions, *i. e.* either a list of `n`

-long lists or a list of `n`

-long dictionaries.

However, when solving a(n) (system of) equation(s) for *one* variable and *not* using `solution_dict=True`

, `solve`

"simplifies" what should be a list of 1-long lists in a list of equations, each of them being a solution for this variable.

This (disputable) simplification has been baked in Sage since Sage's early developers decoded to follow Maxima's conventions (dating from the early 1960's...) and is now a geological axiom. Complain fiercely...

Workaround : use `solution_dict=True`

, whose return values are more consistent (and usually easier to use, anyway...).

HTH,